2007 Fiscal Year Final Research Report Summary
Creation of Proton Mediator Catalysts
| Project/Area Number |
18550028
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Organic chemistry
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| Research Institution | Chiba University |
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Principal Investigator |
YANAGISAWA Akira Chiba University, Graduate School of Science, Professor (60183117)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Organic Reaction / Catalyst & Chemical Process / Asymmetric Protonation / Enolates / Chiral Catalysts |
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| Research Abstract |
In this research we attempted to develop chiral proton sources which make it possible to artificially control the position and reactivity of the proton and to prepare targeted organic compounds selectively with high optically purity in catalytic protonation reaction. During the term of this project, we especially examined novel chiral asymmetric catalysts possessing proton-mediator ability based on chiral Lewis acid catalysts. We have previously discovered that BINAP-AgF catalyst is an efficient chiral catalyst for catalytic asymmetric protonation of silyl enolates with MeOH. Thus, we investigated related chiral phosphine ligands and found that p-Tol-BINAP is able to provide higher enantioselectivity than that given by BINAP. In addition, high enantioselectivity was observed for silyl enolates derived from not only cyclic ketones but also acyclic ketones when a p-Tol-BINAP-AgF complex was used as a catalyst. Furthermore, use of ketene silyl acetals of biologically active α-aryl carboxylic acids such as ibuprofen and naproxen resulted in moderate asymmetric induction with up to 30% ee. In the meanwhile, as for exploration of organic proton-mediator catalysts based on oligopeptides, we tested a dipeptide consisting of aspartic acid and phenyl alanine as a chiral catalyst in the asymmetric protonation of lithium enolates and found that the dipeptide catalyst in combination of a bulky phenol as an achiral proton source gave the corresponding optically active ketones with up to 88% ee.
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